1. Field of the Invention
The present invention relates to a lift-variable valve-operating system for an internal combustion engine, including a subsidiary cam swingably carried on a movable support shaft that is displaceable in a plane perpendicular to a rotational axis of a valve-operating cam and which swings following the valve-operating cam; and a cam follower operatively connected to an engine valve and which is operated to follow the subsidiary cam, wherein the lift amount of the engine valve is varied by displacing the movable support shaft.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 7-63023 discloses a lift-variable valve-operating system for an internal combustion engine in which a cam follower operatively connected to an engine valve is swung by a rocker lever (subsidiary cam) that is swingably driven by a valve-operating cam. The lift amount of the engine valve is varied by displacing the fulcrum of the rocker lever.
In the known lift-variable valve-operating system, oil must be supplied to the contact portions of the rocker lever and the cam follower in order to lubricate the components. Moreover, it is a desirable feature to simplify the structure of such a lubricating structure. However, the lubricating structure in the known system disclosed by Japanese Patent Application Laid-open No. 7-63023 does not have a simple structure.